Mass spectrometry (MS) is among the most informative of analytical techniques. Due to its combination of speed, selectivity, and sensitivity MS has wide ranging applications in areas such as trace elemental analysis, biomolecule characterization in highly complex samples, and isotope ratio determination. However, the large size, weight, and power consumption (SWaP) found in some MS systems generally limits analyses to the laboratory setting.
Much of the SWaP and complexity in MS operation lies in the vacuum systems necessary to attain the high vacuums needed for most mass analyzers (10−5-10−9 torr). Accordingly, one approach to SWaP reduction is the ability to perform MS at high pressure (HPMS). Ion traps, which may be operated at pressures greater than 10−4 torr, can be used as mass analyzers in miniature mass spectrometry systems. However, in some cases, increasing pressures in an ion trap significantly above a few millitorr has a deleterious effect on resolution and signal intensity. The increasing number of collisions with the buffer gas at higher pressures inhibits the ability of the electric field to control the ion trajectories. Increasing the operating frequency (typically a radio frequency or “RF” field) of the trap yields fewer neutral collisions per cycle, reducing the negative effects of high pressure operation but may require a corresponding decrease in trap dimensions to reduce the RF voltage amplitude.
As disclosed in U.S. Pat. No. 8,878,127, Stretched Length Ion Traps (SLITs), like all linear ion traps (LITs), can spatially confine ions into a linear ion cloud, along the length of which ions can move freely and may be particularly suitable for HPMS. The contents of U.S. Pat. No. 8,878,127 are hereby incorporated by reference as if recited in full herein.